cnxTinr.uTioxs TO NORTH AMERICAN ICHTHYOLOGY iv. 



and on the ventral surface. Snout somewhat projecting, with three 

 mult Hid spines; a ridge armed with spines across front of eyes over 

 top of snout; four of these spines larger than others; rostral tentacle 

 club-shaped, trilobate at tip; width of mouth equal to distance between 

 centers of eyes. Head L>.}; width of disk 2. D. I-fl; A. 4; C. 8; P. 

 11; V. 5. Deep water off southern New England. (Goodc.) 

 ( Goode, Proc. U. S. Nat. Mus. 1880, 407. ) 



ORDER W.-PLECTOGNATHL 



(The Plectognalhs.) 



Scapula suspended to the cranium by a posttemporal ; premaxillaries 

 usually cob'ssified with the inaxillaries behind, and the dentary bones 

 with the articular; pharyngeal bones distinct; posttemporal coossilied 

 with the epiotic and undivided; interopercultim a slender rod ; superior 

 pharyngeals laminar, usually vertical and transverse; skin with rough 

 scales or covered with shields or spines, sometimes naked; skeleton 

 incompletely ossilied, the vertebras iu small number; ventral lins re- 

 duced to a single spine or wanting; air-bladder without pneumatic duct. 

 This group is a modified offshoot from A<->tlIi<>i>t<'ri, its nearest rela- 

 tives being the Chcetodontidce and the AcanthuridcQ. (-Asxr^, braided or 

 plaited; fAOo^, jaw.) 



ri<;-!,>,/natlii GiintluT, viii, 207-320.) 



ANALYSIS OF FAMILIES OF PLECTOGXATIII. 



it. Jaws with distinct teeth. 

 b. Ventral fins nhsulrlc. 



c. Teeth narrow; body with an inunnvaldo cara])aoe of hexagonal ])latos; no 

 >|iinoiis dorsal ........................................... Os'i IIACI 1 1 >.!:, l'J7. 



CC. Tufth incisor-like; Ixidy With scales Or movable plates; spinons dorsal presenl. 



]>.M,ISI ID.K. 1'JS. 



an. Jaus.-ach inodilied into a sort of l>eak, without dist inct teeth; no spinous dorsal. 

 (I. I'.ody little compressed : vertical lins dist inct .......... Ti: 1 1:< >n< >NTII>.I-:. I'.'.'. 



(/</. liody much compressed : vertical lins nmre or less eonllneiit around the tail. 



:, 130. 



FAMILY CXXVIT. OSTRACIIDJE. 



(The Tninl--fmJn-n.) 



P.ody short, cuboid, tri<iuet rous 01- pentagonal, covered by a carapace 

 formed of firmly united six-sided plates, the jaws, bases of the fins, and 

 caudal peduncle free and covered by smooth skin. Mouth small; each 

 jaw with a single serio-s of long, narrow teeth. Gill-opening a nearly 



